Organic Gender Bifunctional Compounds The Ground And Excited State Proton Transfer And Spectral Theory

Proton transfer reactions are closely related to the bio-energy transport and genetic gene replication in biological systems. We chose 8-hydroxyquinoline and 6-methyl-4-hydroxy pyrimidine as investigate objects, which can serve as proton-types for structurally related subunits in many important biomolecules. We researched the proton transfer processes of their monomers and dimers in the ground and excited states. The most stable structure and the most possible reaction path were found. Furthermore, their spectrums also have been studied. The main contents of the paper contain four parts, just as follows:1. Density functional theory (DFT) of quantum chemistry method was employed to investigate proton transfer reactions of 8-hydroxyquinoline (8-HQ) monomers and dimers in the ground state. By studying the potential energy curves of the isomerization, the most possible reaction pathway was found. In all possible tautomerization reactions, M1â†'TS1â†'M2 and M2â†'TS2â†'M3 have low reaction barriers, which are 47.3 and 62.6 kJ/mol, respectively. There are three types of hydrogen bond in phenolic dimer and the numbers are six. There are two types of hydrogen bond in quinoid dimer and the numbers are four analogously. So phenolic dimer was more stable than quinoid dimer. The reaction barrier height of M11â†'TS13â†'M12 is 25.7 kJ/mol, which is 36.9 kJ/mol lower than the similar proton transfer reaction of M2â†'TS2â†'M3. It indicates that tautomerization of 8-HQ dimer is easier to proceed than that of 8-HQ monomer. It implied that the hydrogen bond played an important role in depressing the activation energy of reaction. The mechanism of the tautomerization was discussed on the basis of theoretical results.2. The ab initio CIS method was adopted to abtain the first singlet excited-state sructures of 8-hydroxyquinoline monomers and dimers. The solvent effect is modeled using the self-consistent reaction field (SCRF)...